Mesomorphic composition of matter

ABSTRACT

There is disclosed the preparation of a mesomorphic composition of the structure:   WHERE X IS AN INTEGER OF 1 TO 10, TYPICALLY 1 TO 5. The composition is prepared by the reaction of para-n-alkylaniline and para-phenylbenzaldehyde, where the alkyl substituent contains one to 10 carbon atoms.

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United States 1 Dietrich et al.

[ MESOMORPHIC COMPOSITION OF MATTER [75] Inventors: Heinz J. Dietrich;Edward L. Steiger,

both of Toledo, Ohio [73] Assignee: Owens-Illinois, lnc., Toledo, Ohio[22] Filed: July 2, 1971 [21] Appl. No.: 159,554

OTHER PUBLICATIONS Rudolph Gabler of Leipzig, Inaugural Dissertation1939) Kelker et al., Angewonlte Chemie, 22, 903-904 (1969) I June 26,1973 Weygand, Z. Physik Chemie, vol. 53 pp. 75-77 (1942) PrimaryExaminer-Leon Zitver Assistant Examiner-Gerald A. Schwartz Attorney-D.K. Wedding et al.

[ 5 7 ABSTRACT There is disclosed the preparation of a mesomorphiccomposition of the structure:

where x is an integer of 1 to ID, typically 1 to 5. The composition isprepared by the reaction of para-nalkylaniline andpara-phenylbenzaldehyde, where the alkyl substituent contains one to 10carbon atoms.

2 Claims, No Drawings MESOMORPHIC COMPOSITION OF MATTER This inventionrelates to the preparation of mesomorphic compounds. More particularly,this invention relates to the preparation of mesomorphic compounds whichmay be utilized in display type devices.

Mesomorphic materials, typically referred to as liquid-crystalmaterials, are organic compounds in a transition state betweencrystalline solid and normal isotropic liquid forms. Such materials arewell known in the prior art. Likewise, it is known in the prior art touse such liquid-crystal materials in display type devices.

In accordance with this invention there is prepared liquid crystalcompounds of the structure:

where x is an integer of l to 10, typically 1 to 5, by the reaction ofpara-nalkylaniline,

and para-phenylbenzaldehyde,

tron:

where x is as defined above.

Schiff bases are prepared by refluxing equimolar quantities of thep-substituted benzaldehyde and aniline in anhydrous enthanol for about 4to 6 hours. The solvent and water are removed and the residuerecrystallized several times from ethanol until the transitiontemperatures remain constant. The crude yields ranged from 70 to 90percent. The infra-red spectra show a strong band at 1,629 cmcorresponding to the carbon nitrogen double bond in Schiff basecompounds. Other absorption are compatible with the expected structures.

Transition temperatures are determined on a Leitz Ortholux polarizingmicroscope using a Mettler FP-2 heating stage.

N(para-phenyl benzylidene) para-n-butylaniline (where x is 4 in thebasic structure) was prepared in accordance with this invention. Thestructure was analyzed at 87.58 percent by weight carbon, 7.47 percentby weight hydrogen, and 4.54 percent by weight nitrogen compared withcalculated theoretical analysis values of 87.66 percent by weightcarbon, 7.69 percent by weight hydrogen,- and 4.65 percent by weightnitrogen. The compound changed from the crystalline to the nematic phaseat about 120 C and from nematic to isotropic at about l3l.l C.

. trode) members, the conductor members backing each The liquid-crystalcompounds prepared in accordance with this'invention may be utilized indisplay devices, especially of the electronic type.

Such devices typically comprise a thin layer of liquid crystalssandwiched between two sheets of glass. Normally, the thin layer ofliquid-crystal material is clear, but when an electric field is appliedto it, some portions or regions of the material become turbulent so asto scatter light. By controlling the size and shape of the turbulentregions, images can be formed. Primarily, this effect is obtained by useof liquid-crystal materials of the nematic type.

Various embodiments of liquid-crystal electrooptical devices aredisclosed and illustrated in U.S. Letters Patent Nos. 3,401,262 and3,410,999; Proceedings of the IEEE, V01. 56, No. 12, Dec. 1968, pages2,146 to 2,149; The Glass Industry, August, 1968, pages 423 to 425;Chemical and Engineering News, Sept. 30, 1968, pages 32 and 33; PhysicsToday, July 1970, pages 30 to 36; Electronics, July 6, 1970, pages 64 toU.S. Letters Patent No. 3,322,485 to Williams.

It is also contemplated using the liquid-crystal compounds in a chargestorage display/memory device especially multiple gas dischargedisplay/memory device especially multiple gas discharge display/memorypanels which have an electrical memory and which are capable ofproducing a visual display or representation of data such as numerals,letters, television display, radar displays, binary words, etc.

Multiple gas discharge display and/or memory panels of the type withwhich the present invention is especially concerned are characterized byan ionizable gaseous medium, usually a mixture of at least two gases atan appropriate gas pressure, in a thin gas chamber or space between apair of opposed dielectric charge storage members which are backed byconductor (elecdielectric member being transversely oriented to define aplurality of discrete discharge volumes and constituting a dischargeunit. In some prior art panels the discharge units are additionallydefined by surrounding or confining physical structure such as by cellsor apertures in perforated glass plates and the like so as to bephysically isolated relative to other units. In either case, with orwithout the confining physical structure, charges (electrons, ions)produced upon ionization of the gas of a selected discharge unit, whenproper alternating operating potentials are applied to selectedconductors thereof, are collected upon the surfaces of the dielectric atspecifically defined locations and constitute an electrical fieldopposing the electrical field which created them so as to terminate thedischarge for the remainder of the half cycle and aid in the initiationof a discharge on a succeeding opposite half cycle of applied voltage,such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of any conductivecurrent from the conductor members to the gaseous medium and also serveas collecting surfaces for ionized gaseous medium charges (electrons,ions) during the alternate half cycles of the A.C. operating potentials,such charges collecting first on one elemental or discrete dielectricsurface area and then on an opposing elemental or discrete dielectricsurface area on alternate half cycles to constitute an electrical mem-An example of a panel structure containing nonphysically isolated oropen discharge units is disclosed in US. Letters Patent No. 3,499,167issued to Theodore C. Baker et al.

An example of a panel containing physically isolated units is disclosedin the article by D.L. Bitzer and H.G. Slottow entitled The PlasmaDisplay Panel A Digitally Addressable Display with Inherent Memory,"Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco,California, Nov. 1966, pages 541547. Also reference is made to U.S.Letters Patent No. 3,559,190.

In the operation of the panel, a continuous volume of ionizable gas isconfined between a pair of dielectric surfaces backed by conductorarrays forming matrix elements. Typically one or more of the dielectriclayers are photoemissive. The cross conductor arrays may be orthogonallyrelated (but any other configuration of conductor arrays may be used) todefine a plurality of opposed pairs of charge storage areas on thesurfaces of the dielectric bounding or confining the gas. Thus, for aconductor matrix having H rows and C columns the number of elementaldischarge volumes will be the product H X C and the number of elementalor discrete areas will be twice the number of elemental dischargevolumes.

In addition to the matrix configuration, the conductor arrays may beshaped otherwise. Accordingly, while the preferred conductor arrangementis of the crossed grid type as discussed herein, it is likewise apparentthat where an infinite variety of two dimensional display patterns arenot necessary, as where specific standardized visual shapes (e.g.,numerals, letters, words, etc.) are to be formed and image resolution isnot critical, the conductors may be shaped accordingly.

The gas is one which produces light (if visual display is an objective)and a copious supply of charges (ions and electrons) DURING DISCHARGE.In an open cell Baker et al. type panel, the gas pressure and theelectric field are sufficient to laterally confine charges generated ondischarge within elemental or discrete volumes of gas between opposedpairs of elemental or discrete dielectric areas within the perimeter ofsuch areas, especially in a panel containing non-isolated units.

As described in the Baker et al. patent, the space between thedielectric surfaces occupied by the gas is such as to permit photonsgenerated on discharge in a selected discrete or elemental volume of gasto pass freely through the gas space and strike surface areas ofdielectric remote from the selected discrete volumes, such remote,photon struck dielectric surface areas thereby emitting electrons so asto condition other and more remote elemental volumes for discharges at auniform applied potential.

With respect to the memory function of a given discharge panel, theallowable distance or spacing between the dielectric surfaces depends,inter alia, on the frequency of the alternating current supply, thedistance typically being greater for lower frequencies.

In the practice of this invention, it is contemplated that a particularliquid crystal may be prepared and/or utilized alone or in combinationwith other liquidcrystal compositions of the same or different family,e.g. such as a mixture of 2 or more compositions. This may be especiallydesirable since mixtures of compounds may have lower transitiontemperatures than the individual compounds.

We claim:

1. As a composition of matter, a compound having the chemical structure:

where x is an integer of 1 to 1-10, said compound exhibitingliquid-crystal properties.

2. The composition of claim 1 wherein at is 4 and the compound changesfrom the crystalline to the nematic phase at about C and from nematic toisotropic at about 131.1 C.

2. The composition of claim 1 wherein x is 4 and the compound changesfrom the crystalline to the nematic phase at about 120* C and fromnematic to isotropic at about 131.1* C.